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Numerical Modeling of needle-grid electrodes for negative surface corona charging system

Numerical Modeling of needle-grid electrodes for negative surface corona charging system
Numerical Modeling of needle-grid electrodes for negative surface corona charging system
Surface potential decay measurement is a simple and low cost tool to examine electrical properties of insulation materials. During corona charging stage, needle-grid electrodes system is often used to achieve uniform charge distribution on the surface of the sample. There is not much work that describes the effects of the needle grid geometry and voltage levels on the surface potential characteristics. Hence in this work the dynamic surface charge formation has been investigated through simulation. Using COMSOL Multiphysics axisymmetric finite element models have been developed to simulate the gas discharge. A well-known hydrodynamic drift-diffusion model was used. The model consists of a set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. The boundary conditions for the needle-grid-electrode are similar to the needle-electrode except in convection and diffusion model for electrons, the grid electrode top surface was set to convective flux, the sides and bottom was insulation/symmetry; the needle grid was set to flux and its amount was controlled by a secondary emission flux equation. The simulation was performed under the following conditions: the needle electrode was set to -6500V and the grid electrode -1000V. It has been found that an initial impulse current appears at 0.6µs charging and Trichel pulse can be observed for longer charging time. The predicted electric field variations with time (around the impulse current appeared time) along the symmetry axis can be plotted to prove the corona phenomenon. The effect of adding a grid electrode can be clearly seen from the logarithmic plot of electron evolution. Finally, surface charge density on the sample has been obtained for further discussion.
Zhuang, Yuan
fd738637-e5e3-4c0a-ad8e-e011ab0b1314
Chen, George
3de45a9c-6c9a-4bcb-90c3-d7e26be21819
Rotaru, Mihai
c53c5038-2fed-4ace-8fad-9f95d4c95b7e
Zhuang, Yuan
fd738637-e5e3-4c0a-ad8e-e011ab0b1314
Chen, George
3de45a9c-6c9a-4bcb-90c3-d7e26be21819
Rotaru, Mihai
c53c5038-2fed-4ace-8fad-9f95d4c95b7e

(2011) Numerical Modeling of needle-grid electrodes for negative surface corona charging system. Dielectrics 2011, United Kingdom. 13 - 15 Apr 2011.

Record type: Conference or Workshop Item (Poster)

Abstract

Surface potential decay measurement is a simple and low cost tool to examine electrical properties of insulation materials. During corona charging stage, needle-grid electrodes system is often used to achieve uniform charge distribution on the surface of the sample. There is not much work that describes the effects of the needle grid geometry and voltage levels on the surface potential characteristics. Hence in this work the dynamic surface charge formation has been investigated through simulation. Using COMSOL Multiphysics axisymmetric finite element models have been developed to simulate the gas discharge. A well-known hydrodynamic drift-diffusion model was used. The model consists of a set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. The boundary conditions for the needle-grid-electrode are similar to the needle-electrode except in convection and diffusion model for electrons, the grid electrode top surface was set to convective flux, the sides and bottom was insulation/symmetry; the needle grid was set to flux and its amount was controlled by a secondary emission flux equation. The simulation was performed under the following conditions: the needle electrode was set to -6500V and the grid electrode -1000V. It has been found that an initial impulse current appears at 0.6µs charging and Trichel pulse can be observed for longer charging time. The predicted electric field variations with time (around the impulse current appeared time) along the symmetry axis can be plotted to prove the corona phenomenon. The effect of adding a grid electrode can be clearly seen from the logarithmic plot of electron evolution. Finally, surface charge density on the sample has been obtained for further discussion.

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More information

Published date: 13 April 2011
Additional Information: Event Dates: 13 - 15 April 2011
Venue - Dates: Dielectrics 2011, United Kingdom, 2011-04-13 - 2011-04-15
Organisations: Electronics & Computer Science, EEE

Identifiers

Local EPrints ID: 272187
URI: http://eprints.soton.ac.uk/id/eprint/272187
PURE UUID: 18d28423-491e-40cd-ac6f-822b12736fac

Catalogue record

Date deposited: 15 Apr 2011 11:06
Last modified: 18 Jul 2017 06:33

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